Spray dried detergents containing sodium-potassium double silicate

ABSTRACT

A method has been found for increasing the silicate content in spray dried detergents without decreasing the spray dryer throughput. The method involves the preparation of detergent slurries with high solids content by adding alkali metal silicates to the slurries in the form of sodium-potassium double silicate glass. Thus, the amount of water that must be removed in the drying tower is reduced and/or the silicate content can be increased when compared with slurries prepared with sodium silicate solutions.

. United States Patent [191 Weldes 51 Jan. 9, 1973 [73] Assignee: Philadelphia 'uait'z oom m, Philadelphia, Pa.

[22] Filed: Dec. 30, 1970 [21] Appl. No.: 103,002

[52] U.S. Cl ..252/527, 159/48 R, 252/135, 252/539 [51] lnt.Cl ..C11d3/08,C11d7/14,C11d 11/02 [58] Field of Search ..252/135, 539, 531, 527

[56] References Cited UNITED STATES PATENTS 3,639,287 2/1972 Gabler et al..., ..252/l35 3,247,123

4/1966 Schrager etal ..252/1 35 4/1966 Schaatsma et a1 ..252/135 3/1938 Howells et al ..252/l 35 Primary Examiner-Leon D. Rosdol Assistant ExaminerDennis L. Albrecht Attorney-Fred C. Philpitt [57] ABSTRACT A method has been found for increasing the silicate content in spray dried detergents without decreasing the spray dryer throughput. The method involves the preparation of detergent slurries with high solids content by adding alkali metal silicates to the slurries in the form of sodium'potassium double silicate glass. Thus, the amount of water that must be removed in thedrying tower is reduced and/or the silicate content 6 Claims, No Drawings SPRAY DRIED DETERGENTS CONTAINING SODIUM-POTASSIUM DOUBLE SILICATE INTRODUCTION Spray dried detergents are prepared by combining the detergent ingredients in a slurry at about 60 percent solids in a crutcher followed by spray drying this slurry to obtain a granular, free-flowing product of about 10 percent water content. Generally, sodium silicates, which are included in detergents for their detergent building and corrosion inhibiting properties, are added to the crutcher mix as solutions containing 40 to 60 percent water. Most of this water must be removed in the drying tower to give a free-flowing, granular product. The production or throughput of a spray drying tower depends upon the amount of water that must be removed from the slurry to give the apparently dry product. Therefore, if the water added with the silicate can be reduced and the solids content of the slurry increased, then the production of the detergent spray tower will be increased and/or the silicate content of the final detergent can be increased without decreasing the spray tower throughput.

l have found that detergent crutcher slurries of high solids and high soluble silicate content which yield satisfactory spray dried products can be prepared by using a powdered sodium-potassium double silicate glass as the source of alkali metal silicate. It has been thought that alkali metal silicate glasses dissolve too slowly for use in detergents especially spray dried products. Surprisingly, it has been found that sodium/potassium double silicates contribute greatly to the solubility of the final detergent mixture and contribute excellent builder and corrosion resistant properties.

THE INVENTlON The sodium-potassium double silicate glasses can be made by any method, including fusion of sand with potassium and sodium salts or by hydration of a sodium silicate glass with a solution containing potassium alkali. The mixed silicate glass can have a ratio of Na O/K O on a mole basis between 15.0 and 0.1 and the ratio of siO /Na O K on a mole basis can be between 1.6 and 4. The moisture content of the glass can be up to 20 percent and the particle size is such that all of the material passes through a 100 mesh screen. The bulk density of the powdered glass is between 45 and 85 lbs/cu.ft.

The detergent slurry is prepared by blending to 50 percent of the anionic surfactant, such as tridecyl benzene sodium sulfonate; 5 to 50 percent of sequestering agent, such as sodium tripolyphosphate (STPP) and/or organic sequestering agents, such as nitrilotriacetic acid or its sodium salt (SNTA); O to 5 percent of anti-redeposition agent, such as carboxymethyl cellulose (CMC); 0 to 2 percent of optical brightener, and 5 to 30 percent sodium-potassium silicate builder and corrosion inhibitor. Other ingredients, such as soda ash, sodium sulfate, borax and such ingredients generally classified as bulking agents can also be included. This slurry must then be pumped into the mixed flow spray tower and dried with warm air to give a free-flowing granular product containing 3 to percent water.

1 have found that detergent slurries of high silicate solids content can be prepared by using the mixed sodium-potassium silicate glass. These slurries can be pumped and spray dried at this higher silicate content. Because a slurry of increased solids content can be spray dried the throughput of the spray drying tower and the silicate content of the final detergent can be increased. These advantages are particularly evident when larger amounts of the sodium-potassium silicate glass (15 to 30 percent) are included. I

The detergents prepared in this manner dissolved completely in the washing solution and were efficient laundry compounds.

A further understanding of the invention will be ob tained from the following illustrative examples which should not be considered restrictive.

EXAMPLE 1 A slurry of the following composition was made in a crutcher using 1.6 SiO /Na O mole ratio sodium silicate solution of 50 percent solids concentration, and heated about C for 10 minutes.

Linear tridecyl benzene sulfonate 18.0 pbw Sodium Sulfate, anhydrous 14.0 Sodium tripolyphosphate, anhydrous 50.0 Sodium Silicate Solution(1.6 SiO INmO; 50%

solids) 12.0 CMC 1.0 FWA (Blancophor RG, GAF Corp) 0.3 Water 32.0

This slurry was pumped through a spray tower with full counter-current air throughput and jet-type spray; inlet temperature was 320 C, outlet temperature 93 C. The production rate was 50,000 lbs/hour of a free-flowing product with a moisture content of 10.7 percent, a bulk density of 0.35g/cm The product was an excellent laundry compound, readily soluble in the household washing machine.

EXAMPLE 2 The same detergent slurry as in example 1 was prepared using 6 pbw crushed sodium silicate glass of 1.6 mole SiO /Na O ratio with a sizing of all -200 mesh and percent 325 mesh (Tyler), and 6 pbw additional water to compensate for that normally introduced when using silicate solutions. This slurry was heated for 10 minutes at C and then spray dried under the conditions of example 1. A free-flowing product with a moisture content of 10.9 percent and a bulk density of 0.3g/cm was obtained at a rate of 48,000 lbs/hour; this material performed very well as a laundry compound dissolving readily in the washing machine.

EXAMPLE 3 The same detergent slurry as in example 1 was prepared using 6 pbw of a crushed mixed sodium/potassium silicate glass with a mole ratio of 1.99 SiO{/M{O, N a O/K2O l2.0; sizing allmesh, 71 percent 325 mesh. No extra water was added. The slurry was heated for 10 minutes at 80 C and then spray dried under the conditions of example 1. A freeflowing product with a moisture content of 10.8% and a bulk density of 0.33g/cm was produced at a rate of 60,000 lbs. per hour, equivalent to a throughput increase over examples 1 and 2 of about 20 percent. It gave excellent performance as a laundry detergent.

EXAMPLE 4 A slurry composition was prepared in the crutcher containing decreased amounts of sodium tripolyphosphate, some SNTA and an increased amount of 1.6 mole ratio sodium silicate solution (9 percent silicate solids in mix instead of 6 percent as in examples 1 to 3).

Linear Tridecyl benzene sulfonate Sodium Sulfate, anhydrous 13.0 Sodium Tripolyphosphate, anhydrous 38.0 Sodium Nitrilotriacetic Acid, monohydrate 10.0 Sodium Silicate Solution (1.6 SiOJNa O; 50%

solids) 18.0 CMC 1.0 FWA (Blancophor RG, GAF Corp) 0.3 Water 32.0

EXAMPLE The same crutcher composition was prepared as in example 4 using 9 pbw of a crushed mixed sodium/potassium silicate glass with a mole ratio of 1.97 SiO /M,,' "EC/K 0 6.0, sizing all 150 mesh, 80 percent 270 mesh. No extra water was added to compensate for that introduced when using silicate solutions. The crusher mix was heated to 90 C for 10 minutes and then spray dried as in previous examples. A free-flowing product of l 1 percent moisture content and 0.32g/cm bulk density was produced at a rate of 56,000 lbs/hour. Solubility and performance as a household laundry detergent was excellent.

EXAMPLE 6 A low phosphate content crutcher mix was prepared with greatly increased silicate content by incorporating finely crushed sodium/potassium silicate glass with a mole ratio of 2.01 SiO /M O, Na O/K O 3.0, sizing all 1 50 mesh, 87.0 percent -200 mesh.

Linear Tridccyl Benzene Sulfonate 20.0 pbw Sodium Sulfate, anhydrous 20.0 Sodium Tripolyphosphate, anhydrous 16.0 Sodium Nitrilotriacetic acid, monohydrate 16.0 Mixed silicate glass powder (2.01 mole ratio) 16.0 CMC 1.0 FWA (Blancophor RG, GAF Corp) 0.3 Water 40.0

The mix was heated for 10 minutes at 90 C and then spray dried under the same conditions as in previous examples. A free-flowing, readily soluble, non-caking product was obtained with a bulk density of 0.33g/cm and a moisture content of 10.5 percent. Production rate was 60,000 lbs/hour. The product gave washing performance equivalent to standard laundry products.

EXAMPLE 7 A phosphate-free household laundry detergent was produced. A crutcher mix of the composition given below was prepared containing 27 pbw of a crushed mixed sodium/potassium silicate glass with a mole ratio of 2.01 SiOgM O, Na O/K 0 0.9.

Linear Tridecyl Benzene Sulfonate 20.0 pbw Sodium Sulfate, anhydrous 14.0 Sodium Nitrilotriacetic acid, monohydrate 27.0 Mixed Silicate Glas Powder (2.01 mole ratio) 27.0 CMC 1.0 FWA (Blanoophor RG, GAF Corp 0.3 Water 34.0

The slurry was heated in the crutcher and spray dried as in example 6. The free-flowing, granular, non-caking product had a bulk density of 0.3 g/cm and a moisture content of 11 percent. Production rate was 60,000 lbs/hour. lt dissolved completely in the washing machine and gave excellent detergency.

More or less detailed claims will be presented hereinafter and even though such claims are rather specific in nature those skilled in the art to which this invention pertains will recognize that there are obvious equivalents for the specific materials recited therein. Some of these obvious equivalents are disclosed herein, other obvious equivalents will immediately occur to one skilled in the art, and still other obvious equivalents could be readily ascertained upon rather simple, routine, noninventive experimentation. Certainly no invention would be involved in substituting one or more of such obvious equivalents for the materials specifically recited in the claims. It is intended that all such obvious equivalents be encompassed within the scope of this invention and patent grant in accordance with the well-known doctrine of equivalents, as well as changed proportions of the ingredients which do not render the composition unsuitable for the disclosed purposes. Therefore, this application for Letters Patent is intended to cover all such modifications, changes and substitutions as would reasonably fall within the scope of the appended claims.

What I claim is:

l. The method of making a spray dried detergent which comprises a. forming a detergent slurry of about 60-70 percent solids content by blending water with a mixture comprising i. 10-50% of an anionic surfactant,

2. 5-50% of a sequestering agent,

3. 05% of an anti-redeposition agent,

4. 0-2% of an optical brightener, and

5. 530% of a sodium-potassium silicate glass powder in which the ratio of Na O/K O on a mole basis is between 15.0 and 0.1, the ratio of SiO /Na O K 0 on a mole basis is between 1.6 and 4, the particle size is such that all the powder passes through a 100 mesh screen, and the bulk density is between 45 and lbs/cu. ft.,

and thereafter b. spray drying the detergent slurry of (a) under drying conditions that will give a free-flowing, granular product containing 3 to 15 percent water.

2. The method of claim 1 wherein the detergent slurry contains 15-30 percent sodium-potassium silicate glass.

3. The method according to claim 1 wherein said anionic surfactant is tridecyl benzene sodium sulfonate.

4. A method according to claim 1 wherein said sequestering agent is selected from the group consisting of nitrilotriacetic acid, the sodium salt nitrilotriacetic acid and sodium tripolyphosphate.

5. A method according to claim 1 whei'ein said anti: redeposition agent is carboxymethyl cellulose.

6. The method according to claim 1 wherein said v anionic surfactant is tridecyl benzene sodium sulfonate,

i il k t 

2. 5-50% of a sequestering agent,
 2. The method of claim 1 wherein the detergent slurry contains 15-30 percent sodium-potassium silicate glass.
 3. The method according to claim 1 wherein said anionic surfactant is tridecyl benzene sodium sulfonate.
 3. 0-5% of an anti-redeposition agent,
 4. 0-2% of an optical brightener, and
 4. A method according to claim 1 wherein said sequestering agent is selected from the group consisting of nitrilotriacetic acid, the sodium salt of nitrilotriacetic acid and sodium tripolyphosphate.
 5. A method according to claim 1 wherein said anti-redeposition agent is carboxymethyl cellulose.
 5. 5-30% of a sodium-potassium silicate glass powder in which the ratio of Na2O/K2O on a mole basis is between 15.0 and 0.1, the ratio of SiO2/Na2O + K2O on a mole basis is between 1.6 and 4, the particle size is such that all the powder passes through a 100 mesh screen, and the bulk density is between 45 and 85 lbs/cu. ft., and thereafter b. spray drying the detergent slurry of (a) under drying conditions that will give a free-flowing, granular product containing 3 to 15 percent water.
 6. The method according to claim 1 wherein said anionic surfactant is tridecyl benzene sodium sulfonate, said sequestering agent is selected from the group consisting of nitrilotriacetic acid, the sodium salt of nitrilotriacetic acid and sodium tripolyphosphate, and said anti-redeposition agent is carboxymethyl cellulose. 